Michael Jackson's former bodyguard claims the singer was a paranoid maniac ... who ordered members of his inner circle to kill his older brother Randy ... this according to The Sun.

In the interview with The Sun ... ex-bodyguard Matt Fiddes claims, "Michael was caught in a war with his brothers for years, They were desperate to sign him up to a $500 million deal for a Jackson 5 reunion tour."

Fiddes -- a martial arts expert who worked with MJ in the UK and in the US -- explained, "Things reached a head when Randy was trying to force his way past the bodyguards to speak to him in one of his rented homes. Michael ordered him to be shot."

Of course, no one shot Randy ... but Fiddes says, "Randy was so scared he got on the phone and threatened to call the Press. He told the bodyguards, 'If you shoot me the whole world will know about it.'"